I like to think of social media as a public relations tool. In that respect, it can be very useful. You can use social networks to disseminate press releases and other company news, as well as to chat with prospective customers about what types of new products they would find useful. So, it can be used for market research.
However, I don’t think social media is really an effective direct sales tool. Advertisers might be a bit disappointed if they’re counting on it for sales revenue. Ultimately, social networks are only one tool in a marketer’s arsenal. After all, multichannel marketing involves using more than one medium for sales.
Note: I originally posted this comment in a LinkedIn group.